When Tia and Frazier Miller curl up at night under their cozy comforter and crisp 350-thread-count sheets, they scan the sky for shooting stars while being serenaded by a chorus of frogs, coyotes and their neighbor's son practicing his drums. This time of year, nighttime temperatures in their bedroom can dip to freezing. It's not that the couple's new South Bay home is drafty or has thin walls -- they sleep outdoors.

The Millers, who are in their 30s, and many others are returning to a turn- of-the-century Bay Area tradition: outdoor beds. Whether on tracks that roll in and out, in a tree house, on platforms with roll-up canvas walls or simply en plein air nestled beneath a canopy of oaks, outdoor beds are back.

This summer the couple designed and crafted an outdoor bed they sleep on several nights a week, using $500 in hardware-store materials. Built-in benches surrounding a coffee table -- both designed to be part of the bed -- are transformed into the frame by adding several wooden slats stored inside the table. The redwood bed is then topped with a waterproof, deluxe camping- style air mattress, a recent improvement on the futon they were dragging in and out nightly.

Sleeping porches with open-air beds were a defining element of Arts & Crafts homes, an architectural style synonymous with the Bay Area between 1895 and 1920. The progressive movement was "defined by a naturalistic return -- a notion of living a healthier life," says Tim Andersen, the curator for the Los Angeles County Museum of Art's "California Design: 1910," a influential exhibition on the West Coast Arts & Crafts movement. The aesthetic was largely in response to the rise of tightly controlled, rancid urban environments in America, and it romanticized living in the open with exposure to the rigors of nature.

Architectural vanguards of the day -- Bernard Maybeck in the Bay Area and Greene & Greene in Southern California -- included screened or open-air sleeping areas to blur the line between indoor and outdoor living. Kings Road House, a renowned 1922 Hollywood home built by Rudolph Schindler, featured nestlike rooftop sleeping baskets where he and his wife slept nightly. It is believed that the popularity of sleeping porches was in part a response to the tuberculosis epidemic then sweeping the nation. Educational campaigns touted the benefits of outdoor sleeping in minimizing the spread of germs.

ARCHITECT ADVOCATE

The name most often associated with modern-day outdoor beds -- he's built close to a dozen for clients, including the governor of West Virginia -- is Richard Fernau of Fernau & Hartman Architects in Berkeley. He was well aware of the local tradition when he designed his first outdoor bed, for himself. His office at the time was just 50 yards from Temple of the Wings, an eclectic Berkeley home with canvas roll-up walls and outdoor sleeping areas designed by Maybeck as an experiment in outdoor living. "And it's not a coincidence," says Fernau.

But the true inspiration for his beds came from closer to home -- as it does for most who have them. Fernau and his wife spent years pulling their mattress outside onto the bedroom porch for sleeping. "The moment of passion could really be killed if you had to drag the bed out there," laughed Fernau. Now they roll their bed out a sliding bedroom wall to fill a redwood deck that overhangs a gurgling creek.

For the Millers, too, the idea for their bed came from a personal place. Sleeping outdoors is a way of life for this couple. They backpack regularly and spent 60 consecutive nights under the stars when they hiked the Pacific Crest Trail in 1999. For them, an outdoor bed was a way to infuse everyday living with a sense of adventure. "Sleeping -- something that's usually totally mundane -- feels different," says Frazier Miller. "Nights out there are special -- you're so tuned in to everything around you."

For Karla Kelly of Larkspur, outdoor bedrooms were a way to keep an important family tradition alive. As kids, Kelly and her sister, Kristina Woolsey, and their parents slept out all summer long in the yard of the family's Russian River cabin. Later, when they remodeled the simple two-room house, which had been in the family for 50 years, they insisted on places for open-air sleeping. "And my mom, who was then 80, said they had to be comfortable," says Kelly, who co-owns the house with her sister.

So two "outdoor" rooms were created by renowned Bay Area architect William Turnbull Jr. -- one built into a covered porch corner with just two windowed walls, and the other on the front porch with an open view into the breakfast nook. "The rooms aren't assigned to any family member in particular," explained Kelly. "It's spontaneous -- wherever anyone falls asleep."

The experience of sleeping in an outdoor bed -- a combination of creature comforts and striking sounds, lighting and sensations -- is unique. Margaret Simon, 56, who designs interiors for a living, remembers a night in her flea- market four-poster metal bed amid the oaks at her weekend retreat in Calistoga:

"You're looking straight up into the canopy of oaks. And there's dappled light all around. Incredible patterns are falling all around you -- and on you, " recalls Simon. "I woke to coyotes howling up a storm in the valley. It's like I was part of the pack."

NOT JUST FOR SUMMER

The return of outdoor beds may be a reaction to our increasingly closed-off lives. Commuters talk on cell phones in sealed cars, and people send e-mail rather than engage in conversation. "We've gotten way too insulated," says Fernau. "It's a strange mentality, the way we run out of our cars inside to avoid a few raindrops."

Geraldine Laybourne, president of Nickelodeon, sleeps out through the ski season in her dramatic bed perched 1,000 feet above a Telluride, Colo., canyon.

"Snow stacks up on the foot of the bed. It's really lovely," explained Fernau,

the architect of Laybourne's bed and vacation home. Her bed even has a snowplow attachment at the front -- to clear the porch as the bed is rolled out.

As for mosquitoes and other intrusions: Simon, Kelly and others retreat under netting -- Simon's is tied to an oak branch and the four feet of her bed.

Acorns, however, occasionally put even these brave souls over the edge. "Sometimes I lie there worrying one is going to break my nose," says Tia Miller.

Although hardly climate-controlled, outdoor beds make perfect additional space for visitors, and growing families. Most often these needs are occasional -- for a specific gathering or weekend. A wooden bed platform atop an outdoor bathtub and a stand-alone canvas tent structure -- $1,000 from Redwood Empire Awning in Santa Rosa -- are both ways architect Mary Griffin and her late husband, Bill Turnbull, "veered off into eccentricity" and created flexible, unique outdoor sleeping space on the family's Calistoga weekend property.

"We realized that on this land, we didn't need to be inside a house," said Mary Griffin. An outdoor bedroom "just seemed fun -- fun and cheap. And about being able to accommodate people occasionally."

For a wedding shower this fall, Griffin's stepdaughter Ramsey housed the soon-to-be-wed couple atop the outdoor tub, with a view up to the Milky Way.

CALIFORNIA DREAMIN'

The revival of outdoor beds is truly the embodiment of a vision for living in California imagined long ago. When Charles Wheeler, a Bay Area Arts & Crafts architect, defined the California aesthetic to his friend Bernard Maybeck, he said:

"California architecture is landscape design with occasional rooms in case of rain."